Oh...the never ending oil thread!
After having owned 25 bikes over the years including a 480 HP V8 Boss Hoss, I will never understand why anyone would want to screw with the factory recommended oil in a stock engine!
I only ventured from the factory's recommendation because of the Carpenter engine I have which may need more zinc due to the more radical cam.
I use Amsoil Synthetic Z-Rod oil because of its high zinc content but that is the only reason.
How can we second guess the the engineer's recommendations??